The Ambassadors by Henry James (1903). Middle-aged Lambert Strethers is sent to Paris to retrieve a young American whose wealthy parents fear he has taken up with an inappropriate woman, but Strethers sees that the young man is truly happy. Gradually, Strethers finds his flinty provincialism chipped away by Europe’s ease and freedom in this novel whose signature line reads, “Live all you can; it’s a mistake not to.”